Insulation for underground conduits and method of producing the same



Dec. 18, 1956 A. c. KlDD 2,774,333

INSULATION FOR UNDERGROUND CONDUITS AND METHOD OF PRODUCING THE SAME Filed June 3, 1955 IN V EN TOR.

ALEXANDER c. K/DD HIS ATTGR N E 7 ed St2lts Paten Fr" INSULATION FOR UNDERGROUND CONDUITS AND IVIETHOD F PRODUCING THE SAlVIE Alexander C. Kidd, South Orange, N. 3., assignor to Insul-Fil Co., Inc., New York, N. Y., a corporation of New Jersey Application June 3, 1955, Serial No. 512,953

8 Claims. 01. 13 868) This invention relates to insulation for pipes or conduits embedded in concrete or underground, which pipes or conduits are used for conveying or transporting steam, gas, oil, fresh water and sea water, both hot and cold, and encased electric conductors and the like, or lines for light, power or communication systems. This application constitutes a continuation in part of co-pending applicatems, which barrier and the method of producing the same is inexpensive and which will efiectively resist corrosionfrom, and positively obstruct, water vapor, moisture, underground electric currents, soil chemicals, oils, fats, soil bacteria, fungi, parasites, termites and the like, and which'will in turn also retard, if not entirely prevent, the dissipation of the heat in fluid being conveyed when the pipes or conduits are used for transporting fluids.

:It is not new to embed pipes or conduits in protective material. In an endeavor to achieve the aforesaid result, the protective material heretofore used, however, has

not only been expensive to produce, but unsatisfactory in many respects, as an instance, due to the bulk and weight of the same, and consequent excessive cost for transporting the same; due to the fact that it was frequently only obtainable in remote and inaccessible areas, the consequent excessive cost for'long haul transportation of the same; and finally the inability of the. same effectively to withstand corrosion and efiectively to prevent the dissipation of heat in the fluid being conveyedwhen the pipes are used for conveying hot fluids such as steam, hot water, and the like.

These and other features, capabilities and advantages of the insulation and the method of producing the same will appear from thesubjoined detailed description of the same illustrated in the accompanying drawings, in

which 4 Fig. 1 is a cross section more or less diagrammatically showing aiconduit embedded in concrete or underground, and Fig. 2 is a fragmental section along the line 2-2 ofFig. 1. With pipes or conduits embedded in concreteor underground, particularly pipes or conduits for conveying steam or hot water, it has long been an objectto encase the same ina protectivecovering which will constitute" a barrier effectively to resist corrosion from, and positively obstruct, water vapor, moisture, underground electric currents, soil chemicals, oils, fats, soil bacteria, fungi, parasites, termites, and the like, and which will in turn also retard, if not entirely prevent, the dissipation of the heat in the steam or hot water so being conveyed. Ac cording to the present invention as shown in the 2,774,383 Patented Dec. 18, 1956 temperature of 200 F. to 500 F., in actual practice about 400 F., the mixture will divide itself substantially into two main zones, to wit, the plastic zone 3 in which the coated expanded perlite will fuse together, and the sintered or coalesced zone 4 where the heat in the pipe 1 aforesaid causes the high softening point hydrocarbon in a dry powdered state and the coated expanded perlite to be fused together resulting in a sintered substantially solidified mass. Outside of the zone 4 in the area 5 the mixture will remain more or less unaifected or unconsolidated, that is, neitherfused together as is the-case with the plastic mass of zone 3, nor sintered into the substantially solidified mass of zone 4. The aforesaid high softening point hydrocarbon is a by-product in the refinement of petroleum aphalt, generically known as a solvent precipitated asphalt resin, the chemical composition of which consists of the following ingredients and in the proportions by weight as indicated. Assuming thetotal weight to be 241.2 parts, the ingredients now The physical properties of the high' softening point petroleum asphalt hydrocarbon in adry powderedstate are substantially as follows:

Specific gravity at 60 F 1.07-1.10 Softening point, in Fahrenheit degrees 280-310 Bitumen soluble in CCL; V 99.0 Color (0. D.) 373,000 Acid valu Saponification numbers; 11.3

. proximately 2000 F., when it will expand into glass-,

like beads or pearls of about ten to thirty times the original volume of the perlite ore as mined, each pearl The perlite above referred to consists primarily of-a volcanic rockor glass which is extensively found in the No Agua Mountains of Colorado, and has a silica content of about 65% to 70% by weight, an alumina content of 12% to 16%, awater content of 2% to 6%, and small I amounts of the oxides of sodium, potassium, calcium and magnesium. This perlite ore, after having been crushed, graded and 'screened, is quick-heated to apbeing formed into a mass of air cells or voids which make the material not only light in weight but which' effectively convert the same into a heat insulator to retard, if not entirely prevent, the dissipation of the heat from the pipe to be protected; In order to seal off these cells or voids against the entrance of watervapor and the like, the expanded perlite is coated with a high 1 softening point hydrocarbon. The expanded perlite beconsisting of the same high softening point hydrocarbon,

preferably'by blowing-the expandediperlite with thehigh softening point hydrocarbon inn dry powdered state; at. 5 7' supports orspacers 2,. spaced from thebottom of the about 600 Excellent results 'havebeen achieved 'when the dry powdered hydrocarbon is ahigh softening point petroleum asphalt hydrocarbon having a softening point of approximately 325 R, which high softening point is achieved by a solvent precipitat'ed'metho'd re- 10 I sulting in Whatis technically referred to as a solvent pre cipit'atediasphaltj resin In other words, after the perlite ore has been heated to about 2000" F. and expanded,

' then it is allowed to cool untilits temperature drops Ito about 6 00;1- .,'When thehigh ,softeningpoint petro 'leum asphalt jhydrocarbon in a dry powdered form is V blown; onto the same, causing the hydrocarbon'to fuse and coat the expanded perlite' particles upon contact of I the hydrocarbon on the expanded perlite particles. The heating ot the perlite ore to achieve, the expansion de sired aforesaid will preferably take place in a kiln at about 2000" F. v

a It willrof course be obvious that when the heat generated in the conduit 1 exceeds 200 F. and hovers bea inner layer 3, but also to adhere to: the conduit 1' and the fringe of 'the sintered zone or outer 'layer 4, and that the sintered zone :4 willgraduallychangeinto'the' 5 unaffected or unconsolidated areaor zones Where. the

mixture is neither fusedinor 'sintered. Obviously from "an initial temperature of about 400 F. at the pipe or conduitfl, the temperature will gradually diminish in a radially outward direction so that-the temperature will approximate 350 F. on the outer face or the plastic zone 3,:and1v'v'ill diminish still further to approximate 280 F. on thelouter'face of the sintered zone 4. Fur I a,

thermore, with a temperature of about "400 F. at the 40 form which is blown onto the expanded perliteito coatthe; a

pipe 1, zone '3iwould be about'one-half inchin depth 7 radially: andb'e plastic, zone l would be about four to inches in,depth and be sintered or coalesced into a' substantially solidified mass which is impervious to mois- ,ture and provide excellent insulation against the transfer a of heat under all conditions. 'l'he condition of zone 4 gradually changes into the condition of therarea' or zone i 15,; Where the mixture is, neither fused, that is, plastic,"

7 nor sinter'ed, that isfsolidified, but to all appearances practically unconsolidated or loose; 4

Fromtheforegoing, it thus appears that the-invention consists essentially in placing thegpipe tobe protected on supportsin a ditch; or against spacers in the Wall of a a building,mto-space the pipes from'the bottomiof the 7 ditch'or from the wall, thereupbn:-to' pour the mixture of expanded ,perlite coated with a high softeningpoint petro leumfi asphalt-and a quantity of powdered high melting point petroleum asphalt into the ditch or wall space; 1

l QThe high. softening point hydrocarbonior petroleum asphalt is 'appliedin the-dry powdered state; When coat- 0 ing the: expanded 'perlite, the process is substantially as folliows. The perlite as it comesifrom 'th'e mine is heated '1 1 in a kiln to about 2 000 P. Then wheniteoolsto about 600* Rthe high softening point' hydrocarbon oitpetrof leum asphalt in a dry powdered state is blown onto'thej 65. hot perlite and is. immediately" melted and; coats, the; V e perIi-teJ The expanded perlite, d uetofthe, voids created a u in it when it expands'under atempe'rature of*2000 .F. fc'onstitutesan etfective insulation; bearing in mind that :7 :1

insulation generally depends upon the formation of voids "or void areas in'the insulation material. I-Iowever, dueto the. fact 'that the insulation property oi the aperlite i parasites, termites and the like.

1 :of a hydrocarbon 'having ra 'highwsoftening pointki 'a similar high softening point hydro carb cni':Iinf'contact itially'solidified layer; of a sintered mass iofisaid mixture said'inner layer is about ohehalf inch inQdePthLand 'ssaid outer layer is about fourtolsix, inchesindepthle said highsofteningi point hydrocarbon is ajhig I potassium,' lcalcium and magnesium. 7

.heat of about1400 F., an 'in'nei: annularplasticilayer o ringa. highsoftening'pointin'Fahrenheit' degrees of about f I "the like into the voids; For this reason, thepowdered high softening point hydrocarbon is applied to the outer surface of these perlites to; seal off the voids or void areas from the admission of moisture; 0

After, the pipe 1 to be protected is placed upon the ditch or wallythe mixture consisting o f this icoatede'xn panded perlite and a quantity of powdered high-softening point hydrocarbon is 'poured into theditch :or wall area so that the pipe is effectively embeddedor buried inthis a mixture.

, Thereupon, due to, the temperature in 'the' pipes' il," especially when the temperatureirises, to 400 jF., there will be created substantially 'two zones S and 41by the insulationrnixture; Theinner zone '3 will be aplasticior' fluid zone permitting .the pipe 1,rwith contraction and expansion due to change in temperature of the pipe 1, to move in the zone 3 relative to the: substantially solidified' zone 4. Outside of this, inner plastic zone 3, thesecond cylindrical zone 4 'is substantially solidified and. believed to be in a conditiongenerally known as sintered; The pipeto be protected .therefore is disposed-in an inner cylindrical plastic insulation mass. 3 which permits:

'movement of thepipeand an outer sinteredlornsolidified 'tive barrier to water vapor, moisture, stray electric cur:

rents, fats and oils, soil' chemicals, soilrbacteria, fungi, 'f

While the proportion of he quantity of' coated(ex panded perlite relative to the powdered high softening, point hydrocarbon may vary, excellent results have been,

achieved when the 'quantityof coated expanded-perjlitei i a is about 50%-of the mixture by'volume as compared to:

50% of the mixturewbyvolurne of the powdered highsoftening point hydrocarbon. -Whi;le the hydrocarbo'n in powdered form usedsfor' coating-the expanded-perlite it may difier chemic'ally' from the powdered highsoftening; point hydrocarbon with which the coated perlite'is mixed in the final mixture, excellent resultshave beemachieved; when the high softening point hydrocarbon in-powdered same, is the same chemically'as thehigh: softening :point hydrocarbon with which the coated expanded perlite' is mixed in'thefinal mixture. p g. V a a ln otherlwords, the coated; expanded perliteis about i 50% by volume of'therentire mixture where the coating on therperlite amountsto about 57% by volume, and the" 50% by volume of the fina'l mixtureg It is obvious that various changesfand modifications? t maybe madejto-the conduits andjin the .stepspof-zthe j method ZWithOllt departing vfrom thefgeneral spirit? of the invention as set forth intheappendedclaims ,1. Thefcombination 'of'a metal conduitgan inner'annuj- ,lar plastic layer of a mixture of about =50%'.'.by .volum Fahrenheit degrees'of about 2'80to i310 anda ofzaboil 50% by volumeof expanded perlite particle'sjcOated withand surrounding said conduit, andan outersnbs'tan-v 2,} Ihecombinationlas set forth'in claim 1 in V3 The icombination as'sflfp'fth in clairfij V "point Petroleum 7 asphalt 1 hydrocarboniand sard perht contains silica, alumina, waterand the-oxide ofsodiuin H '4.LThe'combination qfv-a' rnetal cohduit'transmittin I mixture of about 5Q% by volume of ahydrocarbon' 280 to 310 and of about 50% by volume of an expanded perlite coated with a high softening point hydrocarbon adhering to and surrounding said conduit in a plastic state when said conduit transmits a heat of about 400 F., and an outer substantially solidified layer of a sintered mass of said mixture merging into said inner layer.

5. The method of producing coated expanded perlite for a pipe insulation consisting in heating perlite ore to a temperature of about 2000 F. to form expanded perlite particles having a mass of cells or voids, allowing the expanded perlite particles to cool to about 600 F., and thereupon blowing a hydrocarbon having a high softening point in Fahrenheit degrees of about 280 to 310 in dry powdered form onto the expanded perlite whereupon the powdered hydrocarbon will fuse and adhere to the perlite particles upon contact, forming a coating of about one to nine by volume of the expanded perlite.

6. The method of encasing a hot medium-carrying conduit with an insulation consisting in embedding the conduit in a mixture of about 50% by volume of a hydrocarbon having a high softening point in Fahrenheit degrees of about 280 to 310 and of about 50% by volume of expanded perlite coated with a similar high softening point hydrocarbon, and transmitting heat at a temperature of about 400 F. from said conduit to said mixture in turn to form an inner plastic cylindrical layer of said mixture movably adhering to said conduit, and an outer substantially solidified cylindrical layer of said mixture merging into said inner layer.

7. The method as set forth in claim 6 in which said inner layer is about one-half inch in depth and said intermediate layer is about four to six inches in depth.

8. The method of encasing a hot medium-carrying conduit with an insulation consisting in heating perlite ore to a temperature of about 2000 F. to form expanded perlite particles having a mass of cells or voids, allowing the expanded particles to cool to about 600 F., thereupon blowing hydrocarbon having a high softening point in Fahrenheit degrees of about 280 to 310 onto the expanded perlite whereupon the hydrocarbon will fuse and adhere to the perlite particles upon contact, forming a coating of about one to nine by volume of the expanded perlite, thereupon embedding the conduit in a mixture of about by volume of a hydrocarbon having a high softening point in Fahrenheit degrees of about 280 to 310 and of about 50% by volume of said expanded coated perlite, and transmitting heat at a temperature of about 400 F. from said conduit to said mixture in turn to form an inner plastic cylindrical layer of said mixture movably adhering to said conduit, and an outer substantially solidified cylindrical layer of said mixture merging into said inner layer.

References Cited in the file of this patent UNITED STATES PATENTS 2,196,172 Billings et a1. Apr. 9, 1940 2,625,512 Powell Jan. 13, 1953 2,668,125 Baker et a1. Feb. 2, 1954 

1. THE COMBINATION OF A METAL CONDUIT, AN INNER ANNULAR PLASTIC LAYER OF A MIXTURE OF ABOUT 50% BY VOLUME OF A HYDROCARBON HAVING A HIGH SOFTENING POINT IN FAHRENHEIT DEGREES OF ABOUT 280 TO 310 AND OF ABOUT 50% BY VOLUME OF EXPANDED PERLITE PARTICLES COATED WITH A SIMILAR HIGH SOFTENING POINT HYDROCARBON IN CONTACT WITH AND SURROUNDING SAID CONDUIT, AND AN OUTER SUBSTANTIALLY SOLIDIFIED LAYER OF A SINTERED MASS OF SAID MIXTURE. 